In recent years, a seal device for sealing a component in a through hole bored in a partition that divides two spaces is generally known as a sealing structure. More practically, the sealing structure seals a periphery of the through hole and an outer circumference of the component disposed therein.
For example, Japanese patent document JP-A-2001-26213 discloses a vehicular air-conditioning unit with the through hole bored in a case that divides an inside air passage from an outer space. The through hole in the case has an expansion valve disposed therein. The gap between the case and the expansion valve is sealed in its entirety with a grommet that serves as a sealing device.
The expansion valve disclosed in the above patent document has a sealing structure formed integrally thereon in a relatively simple form that extends from a body of the expansion valve. The grommet abuts to the sealing structure to complete the sealing structure. The sealing structure for sealing the expansion valve aims to achieve a stable seal by circumventing a problem that arises from a complicated outer shape of the expansion valve.
However, the sealing structure for sealing the air-conditioning unit in the above description has a problem due to an increased volume of the expansion unit having the sealing structure disposed thereon. That is, according to the study conducted by the inventors, a stable seal of the sealing structure for sealing the complicated outer shape of the expansion valve deteriorates when a sealing surface pressure of an abutment portion of the sealing device is not evenly provided in a circumferential direction.